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14 Δεκ 2012 (πριν από 4 χρόνια και 7 μήνες)

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DNA Technology

Recombinant DNA and

Genetic Engineering

Outline

1. Key Concepts

2. DNA Cloning

3. Genetic Engineering

4. Key Terms

5. Conclusions

Key Concepts


Genetic experiments have been
proceeding in nature for billions of years


Genetic changes are brought about by
Recombinant DNA technology


With technology, researchers can isolate,
cut, and splice together gene regions
from different species, and amplify the
number of copies

Key Concepts


Recombinant DNA technology depends on 3
activities


Cutting DNA into fragments


Insertion of fragments into cloning tools like plasmids


clone and identification of desired clone


Genetic engineering involves isolating,
modifying, and inserting genes back into the
same organism or into a different one


Social, ethical, legal, and ecological questions
are raised by the new technology

Glowing mice

Producing Restriction
Fragments


Restriction enzymes


Cut at specific nucleotide sequences


Some create “Sticky Ends”


DNA fragments cut with the same
restriction enzyme will base
-
pair to form
recombinant fragments


DNA ligase


Seals nicks where fragments base pair

Using a
restriction
enzyme and DNA
ligase to make
recombinant DNA

a. Restriction enzyme

cuts chromosomal or

cDNA

c. DNA or

cDNA

fragments


d. Plasmid

fragments

e. DNA fragments

and

modification

enzymes

are mixed

together

f. A collection of

recombinant

plasmids



g. Host cells able
to divide rapidly
take up
recombinant
plasmids


b. Same enzyme

cuts plasmid DNA

DNA Cloning and Genome (DNA) library

The original plasmid is called a

cloning vector

(taxi for delivering foreign DNA into a bacterium)

Human gene Cloning

Complementary DNA (cDNA)


Reverse
transcription

cDNA library

Polymerase Chain Reaction (PCR)

(any piece of DNA can be quickly amplified)


Heat DNA to unwind to single
strands


Add primers that base
-
pair with
ends



Cool mixture to promote base
-
pairing


DNA polymerase assembles
complementary sequences,
doubling number of identical
fragments


Repeat process over and over


Genetic engineering


The goal is to beneficially modifying traits
that the genes influence.

Bacteria


Genetically Engineered Bacteria


Insulin production


Growth hormone


Oil degraders


Pesticide control

Plant

Genetically
engineered cotton
plant having a gene
for herbicide
resistance.

Both had been
sprayed with a
weedkiller


Regenerating Plants from
Cultured Cells

Plant glows in
the dark owing
to a gene
transfer

Genetic Engineering of Animals


Insertion of gene into fertilized egg


Animals produce new products


Cloning


Dolly

Dolly and her first lamb

Applying the New Technology to
Humans


Human Genome Project


3.2 billion base pairs


99.9% of nucleotide sequence is same
for all humans


0.1% account for all genetic differences

DNA Sequencing

Genetic engineering

Recombination DNA

Biotechnology

Gene cloning

Restriction enzymes

cDNA

Cloning vector

Stick ends

DNA ligase

PCR

Genomic library

Polymerase chain reaction

Human Genome Project

In Conclusion


Nature conducts her own genetic engineering
experiments


Recombinant DNA technology allows the isolation,
cutting, and splicing of gene regions



Restriction enzymes and DNA ligase allow new DNA to
be inserted into plasmids


DNA libraries are collections of DNA fragments


Amplification can be done using bacteria or yeast or by
PCR


In Conclusion


Genetic engineering involves the isolation,
modification, and insertion of genes


Recombinant DNA technology and genetic
engineering have potential research and
applications in medicine, agriculture, and
industry